A V-Groove is cut into a mat board from opposing angles that exposes the core of the board. As most mat boards have a white core it creates a white line usually around the mat board opening. A great visual effect is also achieved on black core mat board which the show a black line. V-Grooves are especially helpful from a picture framing design perspective in being able to “tie” multiple images together. Whilst V-Grooves can be cut on older style hand mat cutters, for accuracy computer mat cutters provide a superior result.